Authors
K.D. Edwards, R.M. Wagner, C.S. Daw
Publication
SAE Paper 2004-01-0895, 2004 SAE International Congress &
Exposition
Abstract
A predictive feedback control strategy based on low-order mapping of
system behavior is applied to reduce cyclic dispersion in a model of
lean spark-ignition combustion during fueling transients. The control
strategy utilizes adaptive maps of the steady-state dynamics to identify
appropriate control points and predict future behavior. When future
combustion events are predicted to stray from the control points,
fueling perturbations are made to steer the system back toward the
desired behavior. Overall control perturbations are constrained to
maintain a constant average fuel-to-air ratio. At both steady-state and
transient fueling conditions, the controller successfully suppresses
undesirable combustion oscillations events within a cylinder to allow
for reasonable prediction of measurable quantities of combustion
quality, such as mean effective pressure, at least one cycle in
advance. Specifically, the development of the combustion instabilities
which lead to cyclic dispersion has been shown to follow a
period-doubling bifurcation sequence (Daw et al. 1996; Daw et
al. 2000). Utilizing this knowledge, Davis et al. (2001) demonstrated
proportional feedback control of steady-state cyclic dispersion in a V8
spark-ignition engine by applying appropriate fueling perturbations to
each cylinder (with constraints on cylinder-to-cylinder interactions and
average equivalence ratio).
|
